1. Field of Invention
The invention is related to the field of digital watermarking, and more particularly to informed techniques for coding a watermark message and embedding it into a cover work.
2. Description of Related Art
In recent years, several researchers have recognized that watermarking with blind detection can be modeled as communication with side-information at the transmitter. This has led to the development of informed coding, in which code words or signals used to represent messages are dependent on the cover work, and informed embedding, in which signals are shaped according to the cover work before embedding. Some researchers have employed informed coding to embed large data payloads in images—on the order of 1000 or more bits—but their methods involve only simple forms of informed embedding. Furthermore, as most of these methods are based on some form of lattice quantization, they exhibit only limited robustness against simple valumetric scaling, such as changes in image contrast or audio volume.
The problem remains of how to embed a large-payload watermark message in a digitally encoded work in a manner which will be resilient against typical post-watermarking effects, e.g., signal noise, filtering, scaling, and/or compression, while at the same time maintaining acceptable levels of perceptual fidelity to the original cover work.